Armature advice for the hip region
No, you don't need to add extra bones. You may need to rearrange some of the existing bones.

Remember, when something doesn't work like real life, the best thing you can do is try to mimic real life.

Here's a picture I drew, with proper weights on the leg and a diagram of how the real bone structure is.



Notice how the effects of the leg bone has are very little on the glutes. This will help with crouching as the but won't have to stretch out in order to reach a full squat. Above the hip joint there should be little to no weight, except a little on the abdominal muscles, which need to suck in a little in order for the leg to not collide with them. 

I think this should solve most of your problems; it always works for me.